This invention relates in general to rotary-wing aircraft with a plurality of rotors. More particularly, the invention relates to a rotary-wing aircraft which is especially suitable for still and video photography from the air.
Rotary-wing aircraft with a plurality of rotors are well known in the state of the art. Currently, the most widely used types are quadrocopters, which are defined by four rotors disposed in a single plane and acting substantially vertically downwards. The advantage of rotary-wing aircraft with a plurality of rotors is in general that the three flight axes—the longitudinal axis, lateral axis and vertical axis—can be controlled simply by variation of the thrust of the individual rotors.
Such aircraft are increasingly commonly used for still and video photography from the air. For this purpose, manually controlled or autonomous rotary-wing aircraft similar to model helicopters are employed.
From DE 102005061741A1, a multiple-rotor flying system is known, in which the rotors are realized as collectively variable independently of each other.
From DE 202006013909U1, an aircraft, in particular a quadrocopter, is known, comprising a centrally disposed base element and in particular arms releasably disposed on the base element by means of plug-in or screwed connections.
From DE 102006021182A1, an aircraft is known comprising four horizontal drive rotors, of which two are disposed one above the other sharing a common axis of rotation.
The paper “McKerrow, P, Modelling the Draganflyer four-rotor helicopter, Proceedings of the IEEE International Conference on Robotics and Automation, 26 Apr.-1 May 2004, 4, 3596-3601. Copyright IEEE 2004, http://ro.uow.edu.au/infopapers/100” describes a remote-controlled four-rotor helicopter and gives a theoretical analysis of the dynamics of this helicopter in order to develop a computer control system for stable hovering.
AT 203 876 B describes a helicopter which, in order to extend the possible uses of a helicopter of this type, comprises at least two lifting rotors.
U.S. Pat. No. 6,260,796 B1 discloses a feedback control system for a multi-rotor helicopter.
DE 10 2005 010 336 A1 describes a helicopter provided with three or more lifting units, each of which comprises at least one rotor and at least one electronically commuted direct current motor which drives the rotor. At least one sensor which is used to detect rotational displacement of a rotating component of the lifting unit is provided for, preferably, each lifting unit.
EP 1 901 153 A1 discloses an autonomous miniature helicopter with a plurality of rotors, and a method for controlling such a helicopter by applying real-time adjustment when evaluating flight parameters of the helicopter.
WO 2005/035362 A1 describes cargo transport means provided with transfer means, comprising two parallel arranged systems of rotors, for movement of the cargo up to a height of 80 km above the earth surface.
The aircraft according to the state of the art have in common that loads such as optical or sensor elements, e.g. for still or video photography or environment capture, must be disposed centrally on the aircraft either above or below the plane of the rotors, in order to distribute the load equally between the individual rotors. One consequence of this is that the field of vision of the optical or sensor elements is limited by the rotor plane and other components of the support system. In the case of still and video photography, for example, parts of the support system are visible in the image if its angle of view is too great or the camera is not sufficiently inclined downwards (if it is mounted below the plane of the rotors) or upwards (if it is mounted above the plane of the rotors).
In addition, for reasons that are inherent in the system and independent of the number of rotors, a rotary-wing aircraft must tilt in the direction of flight in order to accelerate in this direction. In some applications, this requires active tilt compensation for the optical or sensor elements, in order to ensure that the object to be captured does not leave the capture area due to the tilting. In the state of the art, if the tilt angles are too great parts of the support system protrude into the capture area as a result of the tilt compensation. This further reduces the unimpeded image area of these elements.